Downriggers are used to hold a fishing line and lure at a selected water depth while trolling. A downrigger typically is mounted to a fishing vessel and includes a reel and boom to pay out a strong downrigger line having a heavy trolling weight attached at the end. The weight is lowered to a preselected depth and causes the downrigger line to hang substantially vertically from the boom even during trolling with the vessel. Attached to the downrigger line near the trolling weight is a fishing line retainer such as a release block adapted to removably receive a snap plug carried at an intermediate location on a standard fishing line suspended from the vessel. The fishing line is terminated by a lure that trails behind the release block at a fixed distance that is set before the release block is tossed into the water. When a fish strikes the lure and pulls with sufficient tension on the fishing line, the snap plug and fishing line are released from the release block and move freely through the water. The fisherman may then reel and pay the fishing line as he attempts to land the fish.
Present downriggers require that the trailing distance of the lure behind the release block be selected before the block is tossed into the water. If the trailing distance is to be adjusted afterward, the block and weight must be reeled in and raised above the water surface so that the snap plug may be released from the release block and moved to a new position on the fishing line. The release block and weight must then be lowered again to a selected depth.
The release tension on known downriggers may be selected from a limited number of values. A typical approach is used by the downrigger from Luhr Jensen and Sons, Inc. This downrigger employs a release block having multiple gaps of slightly varying width that require a different release tension for pulling the snap plug from each gap.
Present downriggers also have a delayed response between the time a fish strikes the fishing line and the fisherman's awareness of the strike. The fisherman is alerted to the strike only after the fish causes visible tension on the fishing line. For instance, if the fish swims upward after taking the lure, the fishing line is slack, and the fish has time to free itself before the hook can be set. In addition, because the only indication of the strike is the delayed bending of the rod or paying out of the line, there may be an additional delay before the fisherman can respond to a strike on an unattended line.
Present downriggers also lack means for precisely indicating the depth at which the lure is being maintained. Typical downriggers use rotation counters on the downrigger line reel to provide an estimate of the depth at which the lure is being held. This estimate is subject to error because the downrigger line does not hang perfectly straight when the fishing vessel is trolling, and because the reel pays out progressively less cable per rotation due to the decreasing effective radius of the wound cable as cable is paid out. While a school of fish may be detected by sonar at a precise depth, the lure depth is known only approximately. Consequently, an error of only several feet in the depth estimate may substantially reduce the number of strikes.
An object of the invention, therefore, is to provide an improved downrigger that overcomes the drawbacks of the prior art.
Another object of the invention is to provide a downrigger wherein the length of the trailing line between the lure and the fishing line retainer may be adjusted without raising the retainer from its depth.
Still another object of the invention is to provide a downrigger having an infinitely adjustable release tension within a given range.
Another object of the invention is to provide a downrigger having an alarm that warns immediately of a fish strike.
Yet another object of the invention is to provide a downrigger having a fishing line retainer that is detectable by a common sonar device.
The foregoing and additional objects, features and advantages of the present invention will be more readily apparent from the following detailed description which proceeds with reference to the accompanying drawings.